When browsers send requests to servers, they receive in return HTTP status codes. Here’s an overview of those codes, in 60 seconds!

An Overview of HTTP Status Codes

Codes starting with 1 give some information while the connection is still in progress.

Codes starting with 2 mean a successful connection was made. 200 says “everything's okay”, but if you see 201 through 206 it means more is happening, like new resources were created or there wasn’t any content to send back.

Codes starting with 3 indicate redirection, like 301 for permanent redirects, or 302 and 307 for temporary redirects.

Codes starting with 4 show there was a client-side error, like 404 if a requested resource doesn't exist or 403 if the user isn't allowed access.

Codes starting with 5 indicate a server-side error, like a failed database connection, or the server being down.